Is Part of:

Abstract:

A detailed map of the structure of the West Spitsbergen Fold-and-Thrust Belt in the shallow part of
the Isfjorden area, Spitsbergen, is presented. The map was constructed from a new dense grid of 2D
multichannel reflection seismic and bathymetrical surveys. Interpretation of two different datasets
gave a possibility to observe and compare tectonic structures detected along the uppermost part of
the seismic sections and those reflected in morphological data at the seafloor. Correlation of the
tectonic structures as expressed in the two datasets shows a good match and three major thrust
faults were identified. The outcropping thrusts display a dominant NW-SE strike. The westernmost
thrust fault (T1) is an out-of-sequence hinterland-directed thrust, whilst the central and easternmost
thrust faults (T2 and T3) represent foreland-directed in-sequence thrusting. The thrusts divide
Isfjorden into three subareas. Subarea 1 is bounded by thrust faults T1 and T2 and comprises
Tertiary rocks surrounded by Jurassic-Cretaceous strata. The structural signature of Subarea 1 is
that of a system of hinterland- and foreland-directed thrust faults, resulting in a seafloor relief
characterized by parallel ridges and lows. Subarea 2 is limited by thrust faults T2 and T3. It
includes an area of Jurassic-Cretaceous strata outcropping on the seafloor. Subarea 3 is situated east
of the main thrust fault T3, and mainly incorporates outcrops of Triassic-Jurassic rocks. Together,
Subareas 2 and 3 are dominated by foreland-directed thrusting with NW-SE and NNW-SSE strike
directions, which are hardly detectable in bathymetric data.

Description:

Published with the title: Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen